1. Field of Invention
The present invention relates to an earphone, and more particularly, to an earphone with adjustable volume of a front chamber between a speaker and a housing.
2. Description of Related Art
With the rapid progress of the science and technology, the electronic product has gradually become light, chic and miniaturized, and people can use the miniaturized electronic products, such as radio or walkman, at anytime and anywhere. Moreover, the personal digital product, such as common MP3 walkmans, cell phones, personal digital assistants (PDAs) or notebooks, has increasingly become popular, and thus being indispensable in the daily life. In addition, the cell phone integrated with functions of both radio and MP3 has immerged.
No matter what kind of electronic products, the earphone has become an essential fitting for the electronic product, so that the user can listen to the sound information provided by the electronic product without interfering others. Moreover, the earphone also provides a preferable sound transmission for the listener, such that he/she can hear and understand the content of the sound more clearly, unlike the circumstance that the sound is unclear when transmitting from computer speakers. Especially, when the user is moving, for example, when doing exercises, driving, conducting acute motions or in a noisy environment, since the earphone is used, the sound transmission will not be influenced.
However, since the size and structure of the ear and the ear canal are different from person to person, and a different person has a different favor for the music, thus, the judgment for the sound quality of the earphone varies as for different persons, and it is hard to meet the requirements of each person. Meanwhile, the frequency response curve of most earphones available in the market is fixed, and if the frequency response on high tone portion or low tone portion of the signal is to be changed, it requires changing the distribution characteristics of the sound field by an electronic equalizer or relevant software. Even though the additional electronic equalizer may change the frequency response of the earphone, the time delay caused by the inductance or capacitance within the electronic equalizer cannot be compensated. Therefore, it is an unavoidable task to improve the structure of the earphone.